The Student Room Group

Transition metals chem (redox)

Hey can someone pls explain the half equation of O2???? Is O2 always oxidised to H2O or what?
O2 is reduced. Oxygen is a much more electronegative atom so would 'steal' the electrons from the hydrogen.
Original post by pondsteps
Hey can someone pls explain the half equation of O2???? Is O2 always oxidised to H2O or what?


O2 is being reduced not oxidised.

What do you need explaining?
Yeah I meant reduced sorry .. But when I did the equation I wrote it as O2 +2e- --> 2O- , isn't this the reduction equation!😭
Original post by pondsteps
Yeah I meant reduced sorry .. But when I did the equation I wrote it as O2 +2e- --> 2O- , isn't this the reduction equation!😭


There are no oxide ions in the products.

The "rules" for balancing redox half-equations are that you can only use:

In acid medium: H+ and H2O
In basic medium: OH- and H2O
Original post by charco
There are no oxide ions in the products.

The "rules" for balancing redox half-equations are that you can only use:

In acid medium: H+ and H2O
In basic medium: OH- and H2O

How do we know which kind of balancing to do???? Like if there were oxide ions in the products would mine have been correct???
Original post by pondsteps
How do we know which kind of balancing to do???? Like if there were oxide ions in the products would mine have been correct???


You can see from the given equation for reaction that there are no oxide ions in the products.

Your second question probably, as you will only get oxide ions formed in things like the combustion of metals.

2Mg + O2 --> 2MgO

IMHO rather too trivial for a redox question.

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